在附錄部分，我們提出記憶體視窗(Memory window)模型架構，透過數學模型去分析不同鐵電材料參數在飽和迴圈下，對非揮發性鐵電場效電晶體記憶視窗的影響，結果顯示在足夠電壓情況下，當剩餘極化或矯頑電場增加時，可增加記憶視窗及鐵電記憶的穩定性。;Industry 4.0 was proposed by the German government in 2013, which can improve the efficiency of conventional industries. To process lots of data, low power consumption and high-speed devices play essential roles. The SRAM possesses the advantage of high speed. If it can recover the data after the power down, the power consumption will be reduced. Recently, ferroelectric-based materials have been widely studied for nonvolatile memory applications because of their advantage of high CMOS compatibility. Therefore, ferroelectric nonvolatile SRAM (FE-NVSRAM) presents great potential to meet the requirements of high-speed operation and low-power consumptions.
This work compares different recall operations for 6T2C NVSRAM using the TCAD simulation with the Preisach model. For the first time, we have studied the impact of device variations on the recall operations. Two recall schemes (Type-1 and Type-2) are compared, considering the worst threshold mismatch (?VTH) scenarios. During the recall operation, as the Ec and εFE reduce, or Pr increases, the NVSRAM shows higher immunity to threshold mismatch. Besides, the Type-2 recall scheme with the optimized ferroelectric area can tolerate 116mV threshold voltage mismatch, which is 4.46 times larger than the Type-1 recall scheme.
In the appendix, we have proposed a framework to analyze the impact of various device parameters on the memory window of FeFET in the saturation loop. The memory window (MW) can increase with the rising of Ec and Pr when sufficient voltage supply is used to program the FeFET, which enhances the MW and improves the reliability.
